<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <div id="app">
        <span v-if="isUser">
            <label for="userName">用户账号</label>
            <input type="text" id="userName" placeholder="用户账号" key="userName">
        </span>
        <span v-else>
            <label for="email">用户邮箱</label>
            <input type="text" id="email" placeholder="用户邮箱" key="emile">
        </span>
        <button @click="isUser = !isUser">点击切换</button>
    </div>
</body>
<script src='../js/vue.js'></script>
<script>
    let app = new Vue({
        el: '#app',
        data: {
             msg:'hello vue.js',
             isUser: true
        },
        methods: {}
    })
</script>
</html>